Described in the patent publication U.S. Pat. No. 5,404,884 are a method and a device for examining corneal tissue of a patient. According to U.S. Pat. No. 5,404,884, a substantially planer laser beam with a slit-like profile is directed through a cross-sectional portion of the cornea. By capturing at least a portion of the light scattered in the cornea, a cross-sectional image of the cornea is obtained. From a multiplicity of such cross-sectional images of the cornea, corneal haze, corneal thickness and corneal topography can be determined comprehensively for the whole cornea. Since the eyes can move relative to the examination device, examination of the entire eye as set forth in U.S. Pat. No. 5,404,884 can lead to inaccuracies, however, because these relative movements are not registered and taken into account. With comprehensive examination of the eye based on the merging of a multiplicity of cross-sectional images, measurement artifacts can result as a consequence of the difficulty of mutual alignment of the individual cross-sectional images.
Patent application EP 1430829 describes an opthalmological device and an opthalmological measuring method in which, by means of a light projector, a beam of rays, for example a light slit, is projected through a cross-sectional portion of an eye, in particular through a cross-sectional portion of the cornea of the eye. A cross-sectional image of at least one sub-area of the cross-sectional portion illuminated by the light projector is captured by image-capturing means, which are disposed in Scheimpflug configuration with respect to the beam of rays. Furthermore, a top view image of the eye, comprising an image of the cross-sectional portion illuminated by the first light projector, is captured by further image-capturing means and is stored assigned to the captured cross-sectional image. For a coherent examination of the entire eye, stored cross-sectional images are positioned relative to each other, on the basis of the assigned top view image. Particularly, the relative positioning of the cross-sectional images is determined on the basis of the image of the illuminated cross-sectional portion included in the top view image, and/or on the basis of light markers and/or visible patterns (e.g. a Placido pattern) reflected on the eye and captured in the top view image. Although the opthalmological device and opthalmological measuring method according to EP 1430829 make possible a coherent examination of the entire eye, taking into consideration the relative movements of the eye with respect to the device, rotations of a spherical cornea are not detected properly in the special case where the cornea rotates around its center.